A cooling system for providing conditioned air to a facility can include a paid cooling subsystem, a free cooling subsystem, a cooling tower subsystem, and/or one or more air handling units or process cooling units. The paid cooling subsystem may include one or more chillers (e.g., variable speed chillers, constant speed chillers, absorption chillers, etc.) and chilled fluid pumps. The free cooling subsystem may include heat exchangers and chilled fluid pumps. The cooling tower subsystem includes one or more cooling tower units and condenser fluid pumps.
Free cooling energy saving opportunities are strongly related to micro-climate weather conditions at the cooling tower subsystem. However, in a complex cooling system involving chiller sub-systems, i.e., paid cooling subsystems, free cooling subsystems and cooling tower subsystems, decisions need to be made as to how much of the total cooling system load can be accommodated by the free cooling subsystem and how much of the total cooling system load can be accommodated by the paid cooling subsystem. From a cost of operation, energy use and carbon footprint perspective it is desirable to maximize free cooling subsystem opportunities; however, paid cooling subsystems are often utilized when free cooling subsystem opportunities are available. This occurs as conditions at the cooling towers near the free cooling subsystem threshold temperatures and humidity conditions in the micro-climate.
Large industrial chillers require a fixed amount of time, e.g., 30 minutes, to reach stable operating conditions. However, operators tend to err on the safe side when weather conditions are marginal. That is, the operators tend to prematurely activate paid cooling subsystems when free cooling subsystems could be generating the needed heat rejection. Furthermore, the operators may make chiller run decisions based upon relatively long term regional weather forecast rather than micro-climate conditions at the cooling tower sub-systems.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.